Streams, creeks and rivers crisscross the Upstate. That topography, as well as clay soils that absorb water slowly, exacerbate flooding risk in an area that has seen rapid development over the past decade — more than 1,800 new homes in the city of Greenville and another 14,000 in the county, according to government records.

Paved surfaces and roofs act as water accelerators, said Cal Sawyer, an associate professor of agricultural sciences at Clemson University.

"You get a slug of water come through, it can do some damage," Sawyer said.

Are you in a flood zone?

Federal, state and local officials know the problem spots around Greenville County and elaborate online maps show where waterways become floodways. Municipal and county workers have been preparing all week by clearing out storm drains and positioning response teams.

In Greenville, East Park Avenue and Byrdland Drive are prone to flooding, said city spokeswoman Leslie Fletcher. In the county, the most vulnerable areas have been addressed through floodplain management and buyouts over the past decade, spokesman Bob Mihalic said.

A motorist drives down North Ocean Boulevard in North Myrtle Beach as it begins to flood on Friday, Sept. 14, 2018.(Photo: JOSH MORGAN/Staff)

Many homes were torn down. Del Norte, Lake Fairfield and Kingsgate were once flood-prone, but the county bought out houses and restored the areas to flood plains, Mihalic said. The most recent area addressed was Coach Hills near Blacks Road and Roper Mountain.

"So you could very much say that the ‘prep’ for preventing flooding has been done over the past decade," Mihalic wrote in an email.

If you are not sure whether your home is in a flood zone, pop your street into the "real property search" site at:

When the list of properties comes up, click on your address. A map with a red outline showing your home should come up. From there, click on "Map Themes" at the top of the page, and choose "FEMA Flood Zones."

Scroll out, and you will see how close your home is to flood zones.

The city of Greenville also has an interactive map that homeowners can use to search for flood information.

Do not attempt to drive through these areas, or any others with standing water, emergency managers in Anderson and Greenville counties said.

"Stay vigilant and use good judgement," Sawyer said. "Get what you need and get in a place where you can sit a while until the storm passes."

The big picture

Chris Starker at Upstate Forever said his biggest concern with the weekend forecast is the potential inability of the ground to absorb water when it's coming down in huge volumes and moving at high speeds across paved surfaces.

Greenville County is currently considering whether to require developers to leave a 100-foot buffer on either side of waterways to help absorb runoff.

Sawyer agreed, saying there is a quantifiable impact to hydrology when communities shift from a forest or farm environment to a neighborhood or city environment.

"I am not anti-development. I think I'm very pragmatic," Sawyer said. "But at the same time, there are ways for us to develop to minimize the impact."

With generally warmer temperatures, Sawyer said, the atmosphere is also able to hold more water. This, he said, has made recent storms "juicier."

"That's simple physics," he said. "That's why storms are a problem when it's warm like this. You won't see these storms in December of January."

Lowering lakes and ponds

With the storm approaching, the U.S. Army Corps of Engineers has opted not to lower Hartwell Lake because of its huge capacity and the likelihood of more flood hazards downstream. But most other lakes and ponds in the Upstate have been lowered in preparation.

Joe Lewis, Martha Collins and her two-year-old daughter Piper take a moment to dry off after checking out how Hurricane Florence conditions have affected the beach in North Myrtle Beach on Friday, Sept. 14, 2018. JOSH MORGAN/Staff

Joe Lewis, Martha Collins and her two-year-old daughter Piper take a moment to dry off after checking out how Hurricane Florence conditions have affected the beach in North Myrtle Beach on Friday, Sept. 14, 2018. JOSH MORGAN/Staff

Steve Mann, operational manager for the Cherry Grove Pier, walks in a parking lot near the pier in North Myrtle Beach as wind and rain from Hurricane Florence begins to dramatically increase on Friday, Sept. 14, 2018. JOSH MORGAN/Staff

Steve Mann, operational manager for the Cherry Grove Pier, waits for wind gusts to decrease before crossing North Ocean Boulevard in North Myrtle Beach to check on their pier on Friday, Sept. 14, 2018. JOSH MORGAN/Staff

Storm chaser Emily Pike laughs as she and her friends Brandon Jarvis and Noah Junot play in a wind tunnel at a North Myrtle Beach parking garage on Friday, Sept. 14, 2018. Wind speeds in the area are beginning to increase as Hurricane Florence creeps into coastal South Carolina. JOSH MORGAN/Staff

Storm chasers Brandon Jarvis, left, and Emily Pike try to suspend themselves in the air in a wind tunnel at a parking garage in North Myrtle Beach as wind speeds begin to increase due to Hurricane Florence on Friday, Sept. 14, 2018. JOSH MORGAN/Staff

Storm chasers Emily Pike, left, and Brandon Jarvis try to suspend themselves in the air in a wind tunnel at a parking garage in North Myrtle Beach as wind speeds begin to increase due to Hurricane Florence on Friday, Sept. 14, 2018. JOSH MORGAN/Staff

A North Myrtle Beach Public Safety officer drives down North Ocean Boulevard as the first rain from an outer band of Hurricane Florence hits the Cherry Grove Pier area of North Myrtle Beach on Thursday, Sept. 13, 2018. JOSH MORGAN/Staff

Haleigh Washington, 13, plays catch at Cherry Grove Beach in North Myrtle Beach as the first rain from a stray outer band of Hurricane Florence hits the area on Thursday, Sept. 13, 2018. JOSH MORGAN/Staff

A North Myrtle Beach public safety officer walks back to his vehicle after informing beachgoers of a 7 p.m. curfew due to the arrival of Hurricane Florence on Thursday, Sept. 13, 2018. JOSH MORGAN/Staff

Beachgoers take advantage of their last opportunity to enjoy the ocean at North Myrtle Beach on Thursday, Sept. 13, 2018 before Hurricane Florence is expected to arrive later this evening into tomorrow. JOSH MORGAN/Staff

Karen Glass, left, and Deborah Murray leave Cherry Grove Beach in North Myrtle Beach after being informed of a curfew due to the arrival of Hurricane Florence on Thursday, Sept. 13, 2018. JOSH MORGAN/Staff

A North Myrtle Beach Public Safety officer drives down North Ocean Boulevard as the first rain from an outer band of Hurricane Florence hits the Cherry Grove Pier area of North Myrtle Beach on Thursday, Sept. 13, 2018. JOSH MORGAN/Staff

Noah Peele, 20, and Haleigh Washington, 13, play catch at Cherry Grove Beach in North Myrtle Beach as the first rain from a stray outer band of Hurricane Florence hits the area on Thursday, Sept. 13, 2018. JOSH MORGAN/Staff

"My boat is upside down with an anchor tied to it and the chairs and table are upside down," Cannaday said. "I think that the winds will be great enough to blow them away."

Broadway Lake in Anderson, whose dam has been damaged in previous storms, was also lowered earlier this week to prepare for the extra water soon to flow in, said Stephen Combs, spokesman for Anderson County's emergency management division.

"This storm has been completely unpredictable form the onset," Combs said. "For us to take it lightly, we would be very misguided."